The speech of speech-handicapped persons is often unclear and sounds included therein are difficult to identify. The speech quality of speech-handicapped persons causes problems, especially when a communications device or network is used for transmitting and transferring a speech signal produced by a speech-handicapped person to a receiver. On account of the limited transmission capacity and acoustic properties of the communications network, the speech produced by the speech-handicapped person is then still more difficult to identify and understand for a listener. On the other hand, regardless of whether a communications device or network transferring speech signals is used, it is always difficult for a listener to identify and understand the speech of a speech-handicapped person.
In addition, at times there is a need to try to change speech produced by a speaker in such a way that the sounds of the speaker would be corrected to provide a better sound format, or that the sounds of the speech produced by that speaker would be converted into the same sounds of another speaker and then the speech of the first speaker would actually sound like the speech of the second speaker.